CVE-2020-17518

CVE-2020-17518 is a high-severity vulnerability in Apache Flink with a CVSS 3.x base score of 7.5. Its EPSS exploit-prediction score of 51% places it in the 99th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-22.

Key facts

Description

Apache Flink 1.5.1 introduced a REST handler that allows you to write an uploaded file to an arbitrary location on the local file system, through a maliciously modified HTTP HEADER. The files can be written to any location accessible by Flink 1.5.1. All users should upgrade to Flink 1.11.3 or 1.12.0 if their Flink instance(s) are exposed. The issue was fixed in commit a5264a6f41524afe8ceadf1d8ddc8c80f323ebc4 from apache/flink:master.

Frequently asked questions

What is CVE-2020-17518?
Apache Flink 1.5.1 introduced a REST handler that allows you to write an uploaded file to an arbitrary location on the local file system, through a maliciously modified HTTP HEADER. The files can be written to any location accessible by Flink 1.5.1. All users should upgrade to Flink 1.11.3 or 1.12.0 if their Flink instance(s) are exposed. The issue was fixed in commit a5264a6f41524afe8ceadf1d8ddc8c80f323ebc4 from apache/flink:master.
How severe is CVE-2020-17518?
CVE-2020-17518 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2020-17518 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 51% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-17518?
CVE-2020-17518 affects Apache Flink. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-17518?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2020-17518 published?
CVE-2020-17518 was published on 2021-01-05 and last updated on 2026-06-17.

References

Affected products (1)

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